Currently, hubs of electric vehicles, electric motorcycles, electric bikes and petrol vehicles mainly use speed-regulating handle or accelerator pedal to directly control current control speed or to control oil supply control speed, or adopt manual control mechanical automatic speed shift mechanism to perform speed shift. Operation of the handle or accelerator pedal completely depends upon driver's operation; which typically causes mismatching of the operation with the vehicle condition, resulting in unstable motor running and locked rotating.
Without knowing the driving resistance, rider of the electric vehicle/petrol vehicle operates the speed shift device only based on his/her experience, and thus unavoidably may face the following issues: 1. When start-up, climbing uphill and under heavy load, the driving resistance increases, which forces the motor speed drop to run in a low-efficiency region, causing the battery to increase current supply, so that the motor is blocked to rotate and is heated, even is stopped to rotate; or the engine stops and gas consumption is too high. 2. Since there is no mechanical gear box to adjust torque and speed, the vehicle can only be widely used in plain area, and cannot satisfy the use in mountain areas, hills and under heavy load condition, which reduces range of applications. 3. For electrical vehicle, the installation space at the driving wheel is limited. Upon installing the motor, it is very hardly to have room for automatic gear box and other new technologies. 4. The vehicle does not have self-adaptive function, and cannot automatically detect, correct and eliminate wrong operation by the driver/rider. 5. When there is a sudden change in speed, motor/engine will be run under unsteady state, which inevitably causes that the output power of motor/engine and driving resistance can hardly match. 6. Continuous running distance is short, climbing hill ability is poor, and application range is limited.
In order to solve the above problems, a series of automatic gear boxes have appeared. However, due to their complicated structure and high cost, it is unable to fulfill the actual applications.
Thus, it is desired to have an automatic speed shift hub, with simple structure, small size, light weight, which can self-adaptively conduct automatic gear shift as the driving resistance changes without cutting off the drive force, to solve the issue that the vehicle cannot satisfy complex road conditions due to small change of motor torque-speed. In addition, less space is needed for installation.